Blackjack

Provably fair

Verify fairness

The session's seed decides every card. Its hash was committed before the first hand; the seed is revealed when the session ends. Each round's cards come from HMAC-SHA256 keyed by the seed over the round's number and the bettor's own seed.

Seed hash

b60d0e981f29ba3bcfa32dba2399dd969eed6512f1548136edd91c8f4aeb473c

Seed

8a9f4380f5e0a3b83c93d286a287234c245e64beddec8271ef104b20e1f80500 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

4d8ab6551066a84d58e731ca4e154811

Commitment

Batch 60,853, Merkle root fcd20d2c63b3b0d8df87d017c0e2b7e608e18bd1201a7f39143b5fc9f7fef25e. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 2d7ead9b37f8fd52073f20abf826a56cfbc5faed15962f86e151b2c96b00baf4
2. f3346100cc2a04863b76fd4cc78742adff9d29d02c52a7cf4437be6600e3ac0c
3. 05b63c1c17b2ad9287a2bd17cd8c0e6a17027f4280aba6472510080f10676391

Checked: the seed hash proves into the root.

To check it yourself, take the session's proof:

1. Hash the seed as above and compare it with the seed hash; prove the seed hash into the root with the Merkle path (keccak256, as for every match).
2. For each round: round seed = HMAC-SHA256(key = seed, "degen.house.round.v1" ‖ 0x00 ‖ u64be(length of the bettor's seed) ‖ bettor's seed ‖ u64be(round)).
3. Key ChaCha20 (RFC 8439, zero nonce) with the round seed and read little-endian 64-bit words; a card is the next word below 2⁶⁴ − 1 − ((2⁶⁴ − 1) mod 52), modulo 52.
4. Replay the round's actions with the game's rules: the cards and the payout must match.

The replay plays every hand rebuilt this way on the server from the same data, and marks any that does not rebuild as recorded.